WO2011062338A1

WO2011062338A1 - Apparatus for removing trace amounts of ammonia from the gas discharged during a carbon-dioxide-collecting process using aqueous ammonia

Info

Publication number: WO2011062338A1
Application number: PCT/KR2010/003403
Authority: WO
Inventors: 김종남; 이광복; 조순행; 박성열; 박종호; 고창현; 범희태; 한상섭
Original assignee: 한국에너지기술연구원
Priority date: 2009-11-17
Filing date: 2010-05-28
Publication date: 2011-05-26
Also published as: CN102612401B; KR20110054273A; KR101039624B1; CN102612401A

Abstract

The present invention relates to an apparatus which efficiently removes trace amounts of ammonia from the gas from which carbon dioxide has been removed and which is discharged during a carbon-dioxide-collecting process using aqueous ammonia, wherein the carbon-dioxide-collecting process separates carbon dioxide from the gas discharged during the burning of fossil fuels.

Description

Apparatus for removing trace ammonia in gas emitted from carbon dioxide capture process using ammonia water

The present invention relates to a device for removing a small amount of ammonia accompanying the exhaust gas from which carbon dioxide is removed in a carbon dioxide absorption separation process using ammonia water from a mixed gas containing carbon dioxide, in detail, a small amount in a carbon dioxide capture device using ammonia water. Trace ammonia in the gas discharged from the carbon dioxide capture process using ammonia water to prevent ammonia loss by using water and to minimize the ammonia content in the exhaust gas by removing irreversible ammonia contained in the flue gas from the capture device by using irreversible chemical reaction It relates to a device for removing it.

With the recent recognition of the seriousness of global warming, countries around the world are struggling to come up with measures to deal with warm gases, and one of the biggest factors of such global warming is carbon dioxide.

The carbon dioxide is generated when the fossil fuel is burned. As a method for capturing or separating carbon dioxide, absorption is widely used, and there are physical absorption and chemical absorption.

In the chemical absorption method, there is an absorption method in which an amine solution having excellent absorption to carbon dioxide is selected as an absorbent, and the carbon dioxide is absorbed chemically in the absorption tower and then separated by changing the temperature in the stripping column. There are many disadvantages such as degradation of absorbent by acidic gas in exhaust gas and deterioration by oxygen, and the price of amine which is absorbent is quite high.

Recently, many methods using ammonia water as an absorbent have been studied, and large scale demonstrations have been made.

Ammonia water is about three times higher than carbon monoxide amine (MEA) aqueous solution, and the heat of regeneration is about one-third. Therefore, when ammonia water is used as carbon dioxide absorber, the size of the device can be reduced and energy consumption can be reduced. In addition, in the case of ammonia water, the price is only 1/10 of the amine, there is no degradation of the absorbent by the acid gas in the exhaust gas, there is an advantage that there is no degradation by oxygen.

However, due to the high vapor pressure of ammonia, there is a considerable amount of ammonia flowing out of the absorption tower unless there is a separate cleaning device, and ammonia is a regulated gas worldwide, making it difficult to implement a clean carbon dioxide capture facility.

Therefore, there has been developed a method and apparatus for washing the ammonia flowing out with water, heating the water used to recover the ammonia, and using the ammonia-free water again for ammonia cleaning.

This technique was developed by the applicant, and has patents 10-70399 and 10-0836709.

They are composed of ammonia scrubbing tower (or absorption tower) and ammonia recovery tower for recovering the washed ammonia as means for removing carbon dioxide separated from flue gas and ammonia contained in flue gas from which carbon dioxide has been removed. In order to satisfy the ammonia emission limit, the scrubber must supply a large amount of water to increase the removal rate of ammonia. Accordingly, the energy consumption of the ammonia recovery tower for ammonia recovery is high, resulting in lower energy efficiency in the carbon dioxide capture process. There was a problem.

In addition, this method was limited in removing trace amounts of ammonia in the treated flue gas.

The present invention was developed to solve the above problems of the prior art, it is possible to efficiently remove the trace amount of ammonia contained in the treated flue gas through a chemical irreversible reaction and reduce the amount of water circulated in the carbon dioxide capture device It is an object of the present invention to provide an apparatus for removing trace ammonia in a gas discharged from a flue gas carbon dioxide collection process using ammonia water.

The apparatus for removing trace ammonia in the gas discharged from the exhaust gas carbon dioxide capture process using ammonia water according to the present invention includes an absorption tower for selectively absorbing carbon dioxide from the exhaust gas using ammonia water; An ammonia washing tower for washing ammonia flowing out of the absorption tower; A stripping column for degassing carbon dioxide from ammonia water absorbed with carbon dioxide; An ammonia recovery tower for recovering ammonia by separating ammonia water produced at the top of the ammonia scrubber and stripping column into ammonia gas and water; And an ammonia removal device for treating ammonia discharged from the ammonia scrubber by reacting with sulfuric acid, wherein the ammonia removal device includes: a pipe to which exhaust gas from which carbon dioxide is removed is supplied; A reaction tank for reacting ammonia contained in the exhaust gas supplied through the pipe with sulfuric acid solution to precipitate ammonium sulfate; Sulfuric acid supply means for supplying sulfuric acid to the reaction tank; It characterized in that it comprises a water supply means for supplying water so that the concentration of sulfuric acid supplied through the sulfuric acid supply means is maintained constant.

1 is a block diagram of an ammonia removal apparatus according to the present invention,

2 is a block diagram of a carbon dioxide capture process according to the present invention.

* Description of symbols on the main parts of the drawings *

1: supply pipe

2: reactor

3: sulfuric acid supply means 3a: sulfuric acid supply pipe

31: sulfuric acid container 32: sulfuric acid pump 33: pH meter

4: water supply means 4a: water supply pipe

41 valve 42 water level sensor

5: Filling

6: water circulation tube

61: circulation pump

7: ammonium sulfate removal vessel

10: ammonia removal device

20: absorption tower

30: stripping tam

40: ammonia recovery tower

50: washing tower

60: heat exchanger

Hereinafter, an apparatus for removing the trace ammonia in the gas discharged from the exhaust gas carbon dioxide capture process using ammonia water according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of an ammonia removal device according to the present invention, Figure 2 is a block diagram of a carbon dioxide collection system having an ammonia removal device according to the present invention.

First, the ammonia removal device according to the present invention is a device for allowing ammonia to react with sulfuric acid to precipitate as ammonium sulfate, as shown in FIG. 1, an ammonia supply pipe 1 to which ammonia is supplied; An ammonia reactor (2) for injecting sulfuric acid solution into the ammonia supplied through the supply pipe (1) to react ammonium with sulfuric acid to precipitate ammonium sulfate; Sulfuric acid supply means (3) for supplying sulfuric acid to the ammonia reactor (2); It comprises a water supply means (4) for supplying water so that the concentration of sulfuric acid supplied through the sulfuric acid supply means (3) is kept constant.

The ammonia removal device configured as described above is installed and used in the exhaust gas carbon dioxide collection system using the ammonia water configured as shown in FIG. 2, and the exhaust gas carbon dioxide collection system using the ammonia water is absorbed to selectively absorb carbon dioxide from the exhaust gas using the ammonia water. Tower 20; A stripping column 30 for degassing carbon dioxide from carbon dioxide-containing ammonia water absorbed with carbon dioxide; An ammonia recovery tower 40 for recovering ammonia by separating ammonia water produced at the top of the ammonia scrubber and stripping column into ammonia gas and water; A washing tower (50) for collecting gaseous ammonia volatilized from the absorption tower (20) to be sent to or discharged from the concentration tower (40); It consists of an ammonia removal device 10 for treating ammonia discharged from the washing tower 50 by reacting with sulfuric acid.

As shown in FIG. 1, the ammonia removal device configured as described above penetrates the lower portion of the ammonia reaction tank 2 installed vertically long and is provided with the ammonia supply pipe 1 so that the ammonia is contained inside the reaction tank 2. The sulfuric acid solution supplied to the lower part and supplied by the sulfuric acid supply means 3 and the water supply means 4 and diluted with sulfuric acid is supplied to the upper part of the reaction tank 2 and sprinkled on the exhaust gas containing ammonia supplied to the lower part. Ammonia and sulfuric acid react to produce ammonium sulfate.

In order to supply the sulfuric acid solution to the upper portion of the reactor 2, a circulation pipe 6 is installed at one side of the reactor 2 of the ammonia removal device, and the circulation pipe 6 is disposed at the lower portion of the reactor 2. A circulation pump 61 for supplying the saturated sulfuric acid solution to the upper part of the reactor 2 is installed.

In addition, the reactor 2 constituting the ammonia removal device configured as described above is provided with a filler 5 for trapping and preventing the ammonia supplied to the bottom from being discharged to the top.

The sulfuric acid supply means (3) is a sulfuric acid container (31) in which sulfuric acid is stored as means for supplying sulfuric acid reacting with ammonia in the reactor (2) to the reactor (2) as described above; A sulfuric acid pump 32 installed at a stop of the sulfuric acid supply pipe 3a for supplying sulfuric acid from the sulfuric acid container to the reaction tank 2 to transfer sulfuric acid to the reactor; It is composed of a pH meter 33 for controlling the operation of the sulfuric acid pump by sensing the acidity of the sulfuric acid solution stored in the reactor (2).

The sulfuric acid supply means 3 configured as described above measures the acidity of the sulfuric acid solution stored at the bottom of the reactor 2 in the pH meter 33, and when the acidity below a certain acidity is measured, the sulfuric acid pump 32 is driven to drive the sulfuric acid reactor. To be supplied inside.

That is, the low acidity of the sulfuric acid solution stored at the bottom of the reactor 2 means that there is little sulfuric acid contained in the sulfuric acid solution, so that there is no sulfuric acid to react with ammonia. Is to increase the amount.

The water supply means 4 detects the amount of sulfuric acid solution to maintain a sufficient amount of sulfuric acid solution stored in the reactor (2) is the sulfuric acid solution of the reactor (2) through the circulation pipe (6) The upper part is circulated to react with ammonia, and if the sulfuric acid solution is not enough, the reaction rate of ammonia and sulfuric acid is reduced, so that the removal rate of ammonia is reduced, so that a sufficient amount of sulfuric acid solution should be maintained.

Accordingly, the water supply means (4) is installed in the middle of the water supply pipe (4a) connected to the water tank valve 41 for intermittent flow, and detects the level of sulfuric acid solution stored in the reactor (2) The water level sensor 42 for controlling the opening and closing of the valve was installed to automatically adjust the amount of water supplied according to the water level.

Of course, even when the acidity of the sulfuric acid solution is too high, water can be further supplied, which opens and closes the valve 41 in accordance with the acidity detected by the pH meter 33 constituting the sulfuric acid supply means (3). It is adjustable.

In addition, an ammonium sulfate removal vessel 7 is installed at the bottom of the reactor 2 to remove ammonium sulfate precipitated by ammonia and sulfuric acid, and ammonium sulfate is disposed at the lower portion of the ammonium sulfate removal vessel 7. A discharge valve (not shown) for discharging to the outside may be further installed.

The carbon dioxide capture system having the ammonia removal device configured as described above is the same as or similar to the configuration of Patent No. 10-0836709, which is patented by the applicant, but will be described in detail below for better understanding.

The absorption tower 20 is to allow carbon dioxide to be absorbed into the aqueous ammonia solution, and the aqueous ammonia solution is supplied to the upper part, and the carbon dioxide is absorbed into the aqueous ammonia solution supplied by introducing a mixed gas containing carbon dioxide into the lower part.

That is, the aqueous ammonia solution supplied to the upper flows to the lower to absorb carbon dioxide from the aqueous ammonia solution.

The aqueous ammonia solution absorbing carbon dioxide is sent to the stripping column 30, and only carbon dioxide is stripped from the stripping column 30 to produce high purity carbon dioxide.

The stripping column 30 removes carbon dioxide by heating an aqueous ammonia solution in which carbon dioxide is absorbed.

The washing tower 50 is a device for collecting ammonia and collects ammonia volatilized and discharged from the absorption tower 20, and the low concentration ammonia water collected from the washing tower is supplied to the ammonia recovery tower 40. The ammonia gas is separated into ammonia gas and water, and the ammonia gas is sent to the lower part of the stripping tower, and the ammonia-free water is supplied to the scrubber tower 50.

The ammonia water from which carbon dioxide is removed from the stripping tower 30 is supplied to the absorption tower 20 to absorb carbon dioxide.

That is, in the carbon dioxide capture process by the carbon dioxide capture system of the present invention, carbon dioxide is collected by circulating along the dotted line as shown in FIG. 2, and ammonia is circulated in the dashed-dotted line to absorb and regenerate carbon dioxide. After the capture of carbon dioxide is complete, ammonia is delivered in the direction of the solid line and provided to the ammonia removal device to remove ammonia.

That is, as described above, it is supplied to the ammonia removal device 10 according to the present invention and reacted with sulfuric acid to precipitate as ammonium sulfate, and the precipitated ammonium sulfate is used as a raw material for fertilizers.

According to the present invention, a small amount of ammonia contained in the exhaust gas discharged from the carbon dioxide capture device using ammonia water can be reacted with sulfuric acid at room temperature to precipitate as ammonium sulfate, thereby saving water and energy required for the treatment of volatilized and flying ammonia. have.

In addition, the ammonium sulfate thus removed can be used as a raw material such as fertilizer, thereby reducing the cost of ammonia treatment.

Claims

An absorption tower 20 for selectively absorbing carbon dioxide from exhaust gas using ammonia water; A stripping column 30 for degassing carbon dioxide from carbon dioxide-containing ammonia water absorbed with carbon dioxide; A washing tower (50) for collecting gaseous ammonia evaporated from the absorption tower (20); An ammonia recovery tower 40 for recovering ammonia by separating ammonia gas and water from the ammonia water produced at the top of the scrubber tower 50 and the stripping column 30; In the device for removing the trace ammonia in the gas discharged in the exhaust gas carbon dioxide capture process using ammonia water comprising ammonia removal device 10 for removing the ammonia discharged without being collected in the washing tower 50,

The ammonia removal device 10

An ammonia supply pipe 1 to which ammonia is supplied;

An ammonia reactor (2) for injecting sulfuric acid solution into the ammonia supplied through the supply pipe (1) to react ammonium with sulfuric acid to precipitate ammonium sulfate;

Sulfuric acid supply means (3) for supplying sulfuric acid to the ammonia reactor (2);

Removing trace ammonia in the gas discharged from the exhaust gas carbon dioxide capture process, characterized in that it comprises a water supply means for supplying water so that the concentration of sulfuric acid supplied through the sulfuric acid supply means (3) is maintained constant. Device.
The method of claim 1,

Apparatus for removing trace ammonia in the gas discharged in the exhaust gas carbon dioxide capture process, characterized in that the filling (5) is installed in the reactor (2) to prevent the ammonia supplied to the inside is discharged to the top.
The method of claim 1,

A circulation pipe 6 is installed at one side of the reactor 2, and a circulation pump 61 for supplying sulfuric acid solution accumulated in the lower part of the reactor 2 to the upper part of the reactor 2 is provided in the circulation pipe 6. Apparatus for removing trace ammonia in the gas discharged from the exhaust gas carbon dioxide capture process, characterized in that the installation.
The method of claim 1,

The sulfuric acid supply means (3) and the sulfuric acid container 31 in which sulfuric acid is stored;

A sulfuric acid pump 32 installed at a stop of the sulfuric acid supply pipe 3a for supplying sulfuric acid from the sulfuric acid container to the reaction tank 2 to transfer sulfuric acid to the reactor;

Ammonia removal device characterized in that it comprises a pH meter (33) for controlling the operation of the sulfuric acid pump by sensing the acidity of the sulfuric acid solution stored in the reactor (2).
The method of claim 1,

The water supply means 4 is installed in the middle of the water supply pipe (4a) connected to the water tank and the valve 41 for intermittent movement of the water;

Apparatus for removing trace ammonia in the gas discharged from the exhaust gas carbon dioxide capture process, characterized in that it comprises a water level sensor 42 for controlling the opening and closing of the valve by sensing the level of sulfuric acid solution stored in the reactor (2).
The method of claim 1,

An apparatus for removing trace ammonia in the gas discharged from the exhaust gas carbon dioxide capture process, characterized in that the ammonium sulfate removal vessel (7) is installed on the bottom of the reactor (2) to remove ammonium sulfate precipitated by the reaction of ammonia and sulfuric acid. .